Fix burnin - when removed from cmdlib, it lost locking functionality.
Fix burnin - when removed from cmdlib, it lost locking functionality.

Also improve the burnin by doing an optional replace-disks.


onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,mbakke/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,apyrgio/snf-ganeti,andir/ganeti,grnet/snf-ganeti,mbakke/ganeti,leshchevds/ganeti,ganeti/ganeti,bitemyapp/ganeti,mbakke/ganeti,andir/ganeti,ganeti/ganeti,dimara/ganeti,apyrgio/ganeti,onponomarev/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,grnet/snf-ganeti,apyrgio/ganeti,yiannist/ganeti,leshchevds/ganeti,yiannist/ganeti,leshchevds/ganeti,bitemyapp/ganeti